Grate



April 11, R. 'r. ROBINSON GRATE Filed April 19, 1930 INVENTUR.

Patented Apr. 11, 1933 l 'i UNITED STATES ROBERT T. ROBINSON, OF PENETANGUEISHENE,; ONTARIO, CANADA.

GRATE Application filed April 19, 1930, Serial No. 445,604, and in Canada May 31, 1929.

This invention relates to grates for use in heaters, furnaces and the like and more particularly to the rotatable type of grate in which the grate is turned to discharge ashes and my object is to provide a grate of this character which may be used in a heater for burning cheap small-sized fuel including screenings and dust thereof.

I attain my object by providing a substantially fiat grate so mounted and arranged relative to the opening in the bottom of a fire pot and to the walls of an ash pit that it forms therewith a passage for air to support combustion. The grate is rotatably mounted and is provided with radially disposed raised ribs which may be curved longitudinally in a horizontal plane to loosen and discharge the ashes from the grate.

The constructions are hereinafter more fully described and are illustrated in the accompanying drawing in which Fig. 1 is a vertical section of the lower part of a heater showing my grate in position;

Fig. 2 a plan view of the grate;

Fig. 3 a sectional detail showing the grate employed in an existing heater having a small ash pit; and

Fig. 4 a plan view ofa modified form of grate.

1 is the grate which is rotatably mounted at 2 on a support 8 which is carried by the radially directed arms 4. These arms are removably mounted in bosses 5 formed on the ash pit walls 6 of the heater 7 The periphery of the grate may be supported by antifriction rollers 8 carried by the arms 4.

The grate 1 comprises a substantially fiat plate having its upper surface provided with raised ribs 9 extending from points near the center towards the periphery thereof and is positioned below the fire pot 10 of the heater to form an air passage 11. By spacing the periphery of the grate from the walls 6 of the ash pit, the passage 11 is continued around the grate to provide a passage for air to support combustion. Preferably the plate is substantially imperforate whereby the passage 11 provides the sole passage for air through the fuel, and fine fuel is prevented from falling through the grate. The area of this passage may be varied by vertically adjusting the plate relative to the bottom of the that the latter will be supported by the grate.

On the underside of thegrate is formed or secured a ring gear 13 which is meshedwith a bevel pinion 14. The latter is secured to a crank operated shaft 15 having one endsuitably journalled in a wall of the ash pit 6 and the other end, in the support 3. By rotating or oscillating the grate the radially directed ribs 9, which are tapered downwardly from their inner ends to the outer ends, are moved relative to the fuel to cut away the ashes from the bottom thereof and convey them towards the periphery of the grate. The ribs pref- I erably have their ends spaced apart and are curved longitudinally in a horizontal plane to facilitate the movement of the ashes towards the periphery of the grate, but any arrangement of the ribs which will cause them to have an outwardly pushing effect as they rotate will answer the purpose of my invention.

From the above description it is obvious that the fuel around the outside and top of the fire will burn first to form a hot mass around a core of comparatively unburned fuel indicated at a. When the fuel forming this core begins to burn all the gases therefrom must pass through and thus be ignited by the said hot mass whereby substantially complete combustion is obtained.

To enable my grate to be used in connection with existing heaters in which the width or diameter of the ash pit 6 is substantially the same as that of the opening 12 in the bottom of the fire pot 10*, a ring 16 may be fitted within the bottom of the fire pot to reduce the size of the opening.

The rectangular grate 1' shown in Fig. 4

"its

grate 1 and the reciprocating grate 1, respectively, so that the same discharging movement of the ashes by the ribs takes place whether a circular or rectangular grate be used.

What I claim as my invention is:

In an apparatus for effecting the combustion of solid fuel of any degree of fineness, in combination, an imperforate-walled approximately cylindrical fire pot, a cylindrical ash pit disposed thereunder, means providing a single circular opening between said fire pot and said ash pit of less diameter than that of said ash pit at a point immediately beneath said opening, a rotary horizontal grate disposed beneath said opening and comprising a substantially flat imperforate circular disc of a diameter greater than that of said opening by an amount suificient to afford a support for the burnt fuel at its natural angle of repose between said opening and the rim of said grate when supported on its horizontal surface, the continuous circular rim of said grate being spaced from the vertical wall of said ash pit to provide the sole passage for air through the fuel thereon whereby the initial combustion and the highest temperatures will occur at the margins of the fuel bed, and raised radiating ribs formed upon the upper surface of said grate, extending from points near the center of said grate substantially to the rim thereof and decreasing in height from the inner to their outer ends where they merge with the surface of said grate, said ribs adapted to move said burnt fuel toward the rim of said grate for discharge over the entire periphery thereof upon periodic rotation of said grate, supporting means for said grate, and means for rotating said grate.

Signed at Toronto, Canada, the 4th day of January, 1930.

ROBERT T. ROBINSON. 

